May 2017

Abstracts of the QSIT Lunch Seminar, Thursday, May 11, 2017

Internal Temperature of Levitated Nano-Particles

Erik Hebestreit – Photonics Laboratory (Novotny group), ETH Zurich

Levitated nano-particles in vacuum have not only shown great potential for the sensing of weak forces and the study of statistical physics, but are also a promising optomechanical test bed for testing quantum mechanics with large masses. These levitated particles are characterized by an exceptional decoupling from the environment compared with other nano-mechanical systems.

We introduce our realization of optical levitation in vacuum, where we utilize the optical forces in a tightly focused laser beam to trap a dielectric particle. We present our efforts in understanding the various interactions of the trapped particles with its environment. In particular we focus on the interaction of the internal temperature of the particle with its center-of-mass motion. This internal temperature is especially of interest for prospective experiments involving quantum states of the levitated object. We show that there is indeed a coupling between internal and center-of-mass temperature which is mediated by the residual gas. Using a theoretical model for this coupling allows us to extract the absolute internal temperature of the particle.

Spin-coherent dot—cavity electronics

Michael Ferguson – Electronic and photonic quantum engineered systems (Zilberberg group), ETH Zurich

Spin-coherent transport in all electronic dot—cavity systems has been recently demonstrated in an experiment with a dot-cavity hybrid implemented in a high-mobility two-dimensional electron gas [Phys. Rev. Lett. 115, 166603 (2015)]. Its spectroscopic signatures have been interpreted in terms of a competition between Kondo-type dot—lead and molecular-type dot—cavity singlet-formation. I will present a framework which can be used to provide guidelines for future device design as well as a thorough understanding of the underlying physics governing the singlet formation. Using these tools I will then propose a future direction which may lead to the design of a long range all electronic entangling gate and to the observation of a Kondo-cat state.